RSSI is a signal strength indication of a wireless communication system. In a typical wireless communication system, particularly in a short-distance wireless communication system (e.g., wireless local area network (WLAN), Zigbee system, Bluetooth system, etc.), the distance between a signal receiver and a signal transmitter can be measured based on RSSI. In the presence of multiple signal transmitters, the signal receiver can calculate the distance from each signal transmitter based on the RSSI, in order to realizing positioning.